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131.
Morohashi N Noji S Nakayama H Kudo Y Tanaka S Kabuto C Hattori T 《Organic letters》2011,13(13):3292-3295
Powdery crystals of p-tert-butylthiacalix[4]arene (2) selectively include EtOH from 1:1 mixtures of MeOH-EtOH and EtOH-PrOH, and EtCO(2)H from HCO(2)H-EtCO(2)H. On the other hand, no acid is included from HCO(2)H-MeCO(2)H, even though MeCO(2)H is included from the neat acid. The origins of these phenomena are discussed based on X-ray analysis of inclusion crystals prepared separately by crystallization. 相似文献
132.
M. K. Kubo Y. Sakai T. Tominaga K. Nishiyama K. Nagamine 《Journal of Radioanalytical and Nuclear Chemistry》1989,136(1):61-66
Diamagnetic muon yields /PD/ in various metal acetylacetonates were measured at room temperature by the muon spin rotation technique. We have found a clear difference in PD between complexes of typical elements and those of transition elements. We suggest that partially filled inner orbitals play some important role in determining the diamagnetic yield in these complexes. 相似文献
133.
Cyano-bridged bimetal assemblies demonstrate novel magnetic functionalities, particularly Prussian blue analogs, which have unique properties. In this perspective, we describe a charge-transfer phase transition, reversible photomagnetism, second harmonic generation and magnetization-induced second harmonic generation, ferroelectric ferromagnetism, humidity-sensitive magnetism, high ionic conductivity, and a coupling effect (which we named spin-ionics) between ionic conduction and magnetic ordering with Prussian blue analogs. 相似文献
134.
This paper presents the comparative studies on the effect of duct height on heat transfer and flow behavior between co-angular
and co-rotating type finned surface in duct. Experiments were performed to investigate the effect of duct height on heat transfer
enhancement of a surface affixed with arrays (7 × 7) of short rectangular plate fins of a co-angular and a co-rotating type
pattern in the duct. An infrared imaging system with the camera of TVS 8000 was used to measure the temperature distributions
to calculate the local heat transfer coefficients of the representative fin regions. Pressure drop and heat transfer experiments
were performed for both types of fin pattern varying the duct to fin height ratio (H
d/H
f) of 2.0–5.0. The friction factor calculated from the pressure drop shows that friction factor decreases with increasing the
duct to fin height ratio (H
d/H
f) regardless of fin pattern and this is expected because the larger friction occurs for smaller duct to fin height ratios.
Detailed heat transfer distribution gives a clear picture of heat transfer characteristics of the overall surface as well
as the influence of the duct height. In addition, different flow behavior and flow structure developed by both patterns were
visualized by the smoke flow visualization technique. 相似文献
135.
Experimental studies on flow visualization and heat transfer measurements of finned surface in a narrow duct were carried
out to understand the flow behavior and its effect on heat transfer. In this experiment, short rectangular fins were attached
to a surface (endwall) with having inclination angle of 20° and exposed to air flow. Several flow visualization results reveal
that horse shoe vortex was formed just at the front of the fin whereas the main longitudinal vortex was formed by the side
top edge of the fin. Some important features of the vortex structure, size and flow reattachment positions were noticed from
the smoke flow visualization. Detailed heat transfer distributions were discussed from the thermal image. Nusselt number shows
that the finned surface achieved average heat transfer enhancement at a factor of four times than that of without fins. 相似文献
136.
137.
Hiroko Nakagawa Kumiko Ohtsuka Katsuhito Sugahara Chika Kobayashi Yuichi Masuoka Koh-ichi Yamada Masami Kawase 《Tetrahedron: Asymmetry》2010,21(6):659-664
Helical [5]thiaheterohelicene 5HM, which rapidly interconverts between P and M enantiomers in solution, was connected to helical l-phenylalanine oligomers with an ester linkage to give peptidehelicenes (5Fn, where n: number of bonded phenylalanines). The characteristics of 5F4 and 5F5 with two types of helixes in a molecule were investigated, particularly in comparison with those of 5F1–5F3 with an incomplete coil of a peptide moiety. l-Phenylalanine peptide chains induced a shift in the equilibrium between the P and M helixes of 5HM toward the P side for all the 5Fns examined. The enantiomeric excess (ee) of the P form increased with a decrease in temperature, together with an elongation of the peptide chains. 5F4 and 5F5 in hot solutions of some solvents formed a gel at room temperature, whereas 5F1–5F3 showed no such behavior. In this gel, the stable helical form of the 5HM moiety in 5F4 and 5F5 was observed to be the M form in contrast to that in their solutions. 相似文献
138.
Toshihiko Sakurai Maki Horikawa Makoto Takafuji Atsushi Kubo Hirotaka Ihara 《Applied Surface Science》2006,253(2):869-873
An l-glutamic acid-derived lipid with a terminal thiol has been synthesized and its corresponding self-assembled structure on Au(1 1 1) surfaces described. The surface morphology of the lipid self-assembled monolayer (SAM) exhibits nano-order patterning, where the height of the monolayer (approximately 1.5 nm) could be interpreted as due to the monolayer structure estimated from molecular models. The molecular orientation in the monolayer is almost perpendicular to the Au(1 1 1) surface depending on the three-point hydrogen-bonding sites in the molecule. 相似文献
139.
A diketone precursor of air-stable bis-2-thienyl-2,6-anthracene was prepared and quantitatively converted to the target acene by photoirradiation of the n-π∗ absorption both in solution and as a film, in air. 相似文献
140.
Tetrabenzoperipentacene: Stable Five‐Electron Donating Ability and a Discrete Triple‐Layered β‐Graphite Form in the Solid State 下载免费PDF全文
Akinobu Matsumoto Dr. Mitsuharu Suzuki Dr. Daiki Kuzuhara Dr. Hironobu Hayashi Prof. Dr. Naoki Aratani Prof. Dr. Hiroko Yamada 《Angewandte Chemie (International ed. in English)》2015,54(28):8175-8178
An oxidative ring‐closure reaction of a tetranaphthylpyrene derivative led to the synthesis of a 56 all‐carbon conjugated tetrabenzoperipentacene. In the single‐crystal X‐ray structure, three molecules make a triple‐layered cluster by π‐stacking, wherein each layer rotates by 120°, and is thus considered a petit β‐graphite. As for the optical properties, the Stokes shift is extremely small (10 cm?1), thus indicating its remarkably rigid framework. The tetrabenzoperipentacene exhibits reversible five‐electron oxidation waves in cyclic voltammetry, and is regarded as a counterpart to the fullerene C60 in terms of stable multicharge‐storage nanocarbon materials. 相似文献